Packaged microelectronic assemblies, such as memory chips and microprocessor chips, typically include a microelectronic device mounted to a substrate and encased in a plastic protective covering. The device includes functional features, such as memory cells, processor circuits, and interconnecting circuitry. The device also typically includes bond pads electrically coupled to the functional features. The bond pads are coupled to pins or other types of terminals that extend outside the protective covering for connecting the microelectronic device to buses, circuits and/or other microelectronic assemblies.
In one conventional arrangement shown in FIG. 1, a device package 20 includes a microelectronic die 50 having bond pads 51 positioned along two central axes. A conductive leadframe 30 having conductive leadfingers 31 connected by an outer rim 38 is positioned over the die 50. The leadfingers 31 are separated from the top surface of the die 20 by an insulating layer 60 on the bottom of the leadframe 30. The leadfingers 31 are electrically coupled to the corresponding bond pads 51 with wire bonds 40, and the die 50 and the leadframe 30 are encapsulated with an encapsulating material 21 (the outer periphery of the encapsulating material 21 is shown in phantom lines in FIG. 1). The leadframe 30 is then trimmed along cut lines 33 and the portions of the leadfingers 31 projecting outwardly from the encapsulating material 21 are bent to form pins or other electrically conductive connectors configured to couple the package 20 to other devices or circuit elements.
Devices such as the package 20 described above with reference to FIG. 1 are typically used in compact electronic products, such as laptop computers and mobile telephones. As these electronic products are made more compact, the dies 50 and the packages 20 are also made more compact. One result of this trend is that the spacing between adjacent leadfingers 31 decreases. One problem with this result is that the signals transmitted along adjacent leadfingers 31 can become capacitively coupled . The capacitive coupling can cause signal errors in one or both of the adjacent leadfingers 31, which can adversely affect the performance and reliability of the electronic products into which the packages 20 are incorporated.